Middle click paste is a very useful feature for a lot of people, but new linux users are not those people.
I personally switched two years ago, and got several people I know to switch too. Everyone I know who switched (including me) was confused by middle click paste.
It’s a hard to intuitively understand action (took me several months until I understood it took the selection for some reason) that is very easy to trigger accidentally, and that duplicates existing functionality.
The people who like it already know it exists, and could just toggle it on.
Of course, on distros not aimed at beginners, like say, debian, it should remain the default.
Former Windows users who expect that to start scrolling. I remember that happening to me when I was new to Linux.
People actually use middle click floaty scroll? But it sucks really bad
I use it all the time in web browsers (Firefox/LibreWolf can do it even on Linux). I learned to use computers on Windows (mainly XP), so as far as I’m concerned, that has “always” been a thing, so why would I not use it.